


Brother in Your Heart

by August_ink



Series: Brother AU [1]
Category: Kingdom Hearts
Genre: Alternate Universe, Alternate Universe - Canon Divergence, Angst, Gen, So yeah, Sora and Vanitas Are Siblings (Kingdom Hearts), and xehanort sucks, the vanitas type angst
Language: English
Status: In-Progress
Published: 2019-11-11
Updated: 2020-12-07
Packaged: 2021-02-01 04:20:10
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 3,880
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21374368
Author URL: https://archiveofourown.org/users/August_ink/pseuds/August_ink
Summary: When Ventus is stabilized by some unknown heart, Xehanort gives him to his old friend Eraqus to train and care for. But not only had the heart supported Ventus, it had also imprinted itself on Vanitas.Xehanort goes in search of this heart, hoping to find it and keep it from interfering anymore with the state of the two halves heart's. Finding the young child—Sora—he kidnaps him to keep him under his thumb.
Relationships: Sora & Vanitas (Kingdom Hearts)
Series: Brother AU [1]
Series URL: https://archiveofourown.org/series/1540930
Comments: 48
Kudos: 110





	1. First Meeting

**Author's Note:**

> I dunno how well this'll go. It was a fun idea and I thought I'd practice writing with it.

### Chapter One

Vanitas sat crouched on the ground. The bare rock earth of the keyblade graveyard around him. Dust was picked up by the wind and blown around in small clouds to float their way into a rock face and drift to the earth once more. The wind was thin in air but full of dust as it brushed against the rock hard earth and up to meet with the sky.

_ Stay here. Don't leave. Kill them. _

That's what his master had said before he left. Kill the many creatures that surrounded him, only slightly animal, their pure red eyes empty of joy. Sorrow and hate were the only things you felt from their gaze—horrible creatures made from his own unstable emotions. He cringed at the things in disgust. He wished to wipe them out, out of his sight and gone. But didn't the Old Man know that it hurt? The wind, the dust, his breath. Everything. He hurt all over, and those _ things _ hurt him to. He could feel them pulsing to the beat of his own heart. Feeling them so close to him made him sick, all the hate and loneliness exposed to the harsh world. To put it out of its misery would be the best thing, but it involved pain. It was a part of him, he felt what they felt, as he killed them. But in the pain there was strength. His master had told him that fighting them would make him strong, stronger than them, strong enough to not feel the pain, strong enough to take back what was his, and none could stop him.

Hours passed in the rocky graveyard as Vanitas took out his anger on his sorrow and lashed out at his hate, only to be left with more anger to destroy. Suppression. It was a lesson in self-control and suppression. If he could control and suppress these feelings then they couldn't take hold and become whole creatures with substance.

Exhausted and hurting all over he sunk to the ground, panting and glowering at the assorted creatures of his various emotions. Where was that Old Man? What was he doing that took him so long?

Vanitas scooted himself backwards and getting to his feet climbed the nearest high rock and peered into the distance. In all directions he stared and couldn't spot any hunched figure, but the clouds of dust made it hard to see very far. Slipping back down off it he placed himself on the ground again, his back pressed against the rock wall giving him a sense of safety, tucked away, not easy to be spotted but he could watch. Maybe when his Master came back he would have a hard time finding him. It's what he deserves for leaving him like that so long.

The wind picked up higher and Vanitas listened to it as it howeled over the barren ground and through the narrow cliffs creating sharp whistles. Rocks. Cliffs. Dirt and dust. Nothing was alive here. The land bore its name well, a graveyard of a world without happiness. A sun shone down on the dead earth, but its warmth never reached it. How could anyone ever really live here? Why had the Old Man chosen this world, a graveyard? Propped comfortable against the rock, head laid on his shoulder he heard the footsteps of his approaching master, solid quiet strides as his boots clicked upon the bone-dry ground. He could hear him pausing every now and then, grumbling to himself.

_ Perhaps I actually fooled the coot and he can't find me. _ Vanitas smirked at the thought.

A small _ thud _ snapped his attention back. Straightening and tense he cocked his ear to listen. Had the Old Man fallen over? Was he having a heart attack? Vanitas scooted himself forward and peered out from his rock coverage to see his master standing fine, growling down with annoyance and little patience at a young toddler who was picking himself up from the dust. On his knees, the young child bare foot on the cold earth, he pressed his small chubby hands upon the ground and pushed himself up, sighing heavily. His brown locks bobbing with his head and his teary eyes settled on Vanitas's face.

Vanitas stared back in shock. Though the face was small and young—still with it's chubby baby cheeks—and the eyes bright blue like the ocean, it was his face. Like gazing into a mirror he stared at the child who wore his own face.

And the child smiled.


	2. Acquaintances

**Summary for the Chapter:**

> Vanitas is slowly warming up to the small child, and baby is being cute baby.

**Notes for the Chapter:**

> Well I guess I'm posting this in small parts, okay. I can role with that. Sorry for the short chapters... :/

### Chapter Two

The small fat toddler sat on the packed earth floor of what Xehanort called his “house”. Halfway underground, in the side of a cliff it was barely noticeable. It was small though, and the snug close rooms under the earth made for a warm place to retreat from the chilled earth above.

Vanitas sat in the corner of the room watching the child as it sniffed and rubbed it's fist over its mouth. The pathetic thing had just finished wailing it's head off, apparently it didn't want the Old Man to leave it alone. Stupid thing. It'll learn soon enough it does.

He squinted at the fussy thing racking his brain for why his master would want it. What in the world did this baby provide? He hadn't yet told him but Vanitas guessed it had something to do with them being identical. All he told him was that he must watch it, and keep it from danger.

The toddler was sniffing and glancing about, trying in vain to find the old man. To Vanitas's horror it's eyes found Vanitas in his corner and it rested its gaze there. A little smile tugged on the fussy child's lips. It sniffed and began making its way toward the hunched boy in the corner glaring at him. No, no. Vanitas did not want that thing sitting next to him, no. It felt _ weird _, and it was gross. But unfazed by Vanitas's snarl the small thing snuggled into the corner next to him, squished against his side. Vanitas stared at the child, and the child stared back, two faces mirroring each other. One full of hate and a lonely pain. The other full of sorrow, and it's lonely hope. Vanitas felt a kind of peace, the swirling darkness seemed to quiet and rest, and instead there was a small warmth, like reassurance.

The child sighed and nestled himself into Vanitas's lap, resting its head on Vanitas's strong arm. Looking down at the young child Vanitas's contempt for it disappeared, here it was snuggled next to him. Maybe he wasn't so horrible like this. Maybe he didn't need another half to be fine.

“You sleepy?” Vanitas tried to sound gruff. He didn't want the kid to get the idea he actually cared.

A mumble and a nod was the only response he got.

It wasn't long until it seemed the child had fallen asleep curled up with him. Vanitas didn't know why the child had chosen to sleep by him, how he had the trust to do it, and why it made him feel like this. What was this emotion, was it one? Like the sun rising in the morning, or the clouds clearing from a storm, all his pain seemed swept up. It wasn't gone it was there, he could feel it throbbing, but it felt held, it wasn't breaking and bleeding. It somehow felt...right.


	3. Patience and Practice

**Summary for the Chapter:**

> Vanitas over here traumatizing a kid and babey just making friends.

“I have things to attend to, you will watch the child.” Xehanort mounted the steps out of the door leaving Vanitas with few instructions on how to structure the day with him gone.

Vanitas mumbled to himself and shot a glance at 'the child’ he had to babysit now. If it weren't here he'd probably be going with the old man. The child looked back unfazed and blinked twice, thumb in its mouth.

“Come on then,” Vanitas growled through gritted teeth at it walking past to the kitchen, “let's get the beans going.”

He hated it. It was either sobbing or the most carefree thing in the world. Everything revolved around it, if its world wasn't how it wanted it it cried its pretty head off, and when it wasn't crying it was just too happy. It was unnerving, it didn't feel right or natural. How could anything be that happy? It must not be actually real, it was just an “it”, because how could it be natural? If it really was real it would realize there was nothing to be happy about.

But as Vanitas thought this and went about cooking cold black beans the child followed him like a dog, right at his heels happily watching his every move, chattering away nonsense Vanitas didn't even bother to listen to.

After reheating the cold beans (and slightly burning them) they sat at the small table and ate them. Vanitas giving the child a cold hard stare, and the child slowly eating obediently. Silence hanging between them except for the clink of their spoons. Vanitas stared long and hard at it, what in the world was he supposed to do with this thing? It did nothing all day long, and he had things he needed to do! Practice and training. But now he had this baby to watch. He could see his time frittering away into a useless waste of keeping a nuisance under control. 

Leaving the dishes where they lay he picked up the child by the back of his shirt and took him outside. The child squirmed and fussed but seeing Vanitas’s grib was firm it obediently hung like a kitten being held by the scruff. 

Marching it outside, his annoyance scrambling at his feet and out of the way he brought it to a rock and roughly set it down. With a fuss the child squirmed and hugged it's knees looking at Vanitas with large eyes and a pouty mouth.

“No you be quiet, I'm busy. You just sit there.” Disgust breaking off from him and joining the others of its kind.

The child stared in fear at the large unversed and glanced uncertainly at him a few times before scooting away. 

_ The pathetic thing can't handle it. Why is it here? _

Vanitas summoned his keyblade, taking the weight of it in his hands, and shifting his feet into a suitable stance he began to kill the unversed around. Every blow stinging, he ached and felt queasy, but his master had told him it was the only way he could be strong. The darkness in his heart pulsed and urged him on, like a voice driving him to greater heights.

He ignored the child. Let it cry.  _ He _ was stronger than that. Swinging his blade he sliced through the large unversed, pain filled his vision and floods poured at his feet. He stumbled on his footing and turned himself around to finish taking it down, but he was tired and weak. It took him several blows to take it down and he was shaking by the time he was done with all the large unversed in the area. Drawing large breaths of air he leaned on his keyblade and looked about at the many small floods and (the bunny ones) scattered around in the dust. His darkness throbbed, he could feel it like a storm slowly rising in the sky. It ached as it throbbed, like it would break through the fragile shell of his torn heart and spill all around, like his emotions. Was nothing his own to keep? Somewhere, deep in him hidden under the layers of throbbing darkness he felt weak, like he was ready to shatter. He didn't know where because all that darkness—his might, was pulsing through him in his being like blood in his veins, giving him purpose and life. So what was there to feel weak? Was it his own feeble body, unfit and forign for the heart it held? His body shuddered and he gulped in air. 

A cough brought his attention to the child he left on the rock. It sat huddled and terrified, one hand over its face and the other waving dust away. It was shaking from the brisk air and quietly moaning. Vanitas sighed and sent his keyblade away, and kicking unversed away from him to go lay in the dirt he wearily made his way to the child. 

“If you were cold you should have brought something.”  _ Does it have anything else? What does it matter it's stupid. _

It shook its head and pulled it's hand away from it's face to look Vanitas up and down.

“No? No what.” He scowled down at it, clearly not wanting an answer.

The child glanced around at the remaining unverse and shuddered, scooting itself closer to Vanitas. 

Vanitas followed his gaze to his leaked emotions; small, weak, broken away from it's true source, and horrific. Like a mirror reflecting himself, and he hated them for it. And then there was his own hate staring back at him.

Something touched his hand and his skin burned. He hissed in pain and quickly pulled his hand to him looking down to see the child beside him, gently reaching for his hand. The concern was written all over his face, Vanitas didn't need unversed to see what it was feeling. 

“What are you worried about, you think they're gonna eat you? Well you're right.” 

The child drew slightly away from him and glanced at the unversed and shook it's head. 

“You're hurt?”

Vanitas looked down at it. That was the first thing it had done besides cry. His surprise quickly checked before it could become anything he relaxed himself and crossed his arms.

“No.”

“You  _ looked _ hurt…” It hugged it's chilly arms and looked at the ground, “I could hug it away…”

Vanitas snorted. Of course it would say something so stupid when it finally opened it's mouth.

“Well why don't you hug that and see if it fixes it.” His voice dripping with sarcasm he gestured at a flood melting in and out of the dust.

The child's gaze followed his hand and stared. After a moment of thought it gave a short nod and began inching towards it.

“Okay…” Mumbling in a low tone almost unrecognizable.

Vanitas rolled his eyes and leaned against the large rock, his aching body glad for the break. He watched as the child scurried around in the dirt trying to get a hold of the flood, upset grunts and whimpers coming from him every once in awhile.

Eventually it got a grip on one and squeezing it tightly to itself to stop the squirming it sat down with it. 

Vanitas winched and felt like squirming himself with how tightly it squeezed the flood. 

The child began stroking the flood's head in an effort to calm it down and hugged it close, rocking gently. The flood being larger then the child barely fit in its lap, like an oversized teddy bear. 

The child's grip began to relax as the flood settled into the hug and excitedly the little thing patted and hugged the void creature. 

"See I did it!" its beaming face looking up to Vanitas for affirmation, "It's good!"

Vanitas looked back, his gaze cold and indifferent. Roughly pushing against the rock he righted himself to his feet and limped over to his emotion, gazing down at the two of them.

"No don't…" looking slightly terrified it held the flood closer and leaned away from Vanitas, "It's gonna be good…"

The flood chirped and nestled into the child's shirt making it giggle, the churning emotion and empty void inside it forgotten.

Forgotten? How could it forget? That was all it knew. How could it be content, he never was. How would it know how? Now even the monsters of his emotions could be happy when he can't? 

Vanitas could feel a warm good feeling from it, but it wasn't it's own. Where would it borrow feelings from beside him?

He critically stared at the happy child with the flood and its borrowed emotion. The happy child who clumsily picked up the blue creature in its chubby arms and began dragging it back to the dirt hovel. 

_ Well let it do as it pleases with the thing, it'll probably kill it in its sleep. It deserves it for being so dumb.  _

Seeing as he had rested far too long, and the child taken care of, he employed himself back to his endless and brutal task. 

**Notes for the Chapter:**

> Alert! The child spoke!!
> 
> Yeah sorry guys for being so slow with this, and, serving it in such small bites :/ I'm trying to make these chapters longer.


	4. A New Friend

**Summary for the Chapter:**

> Sora makes a friend and eats some bread. Vanitas is just a mood.

### Chapter Four

The stars settled in the heavens above the graveyard and Vanitas found himself alone, cold, and numb. 

He felt nothing. No emotions. No pain. Just a numb aching penetrating body and soul. With nothing left to feel there was nothing to kill, and with checked relief he hobbled back to the hole in the ground he slept in. 

Upon entering Vanitas found the child laying on the dirt-packed floor, the flood draped across its chest, and the empty bean pot laying beside them.

Too tired to care about his missing dinner or the flood being handled he slumped against the wall and slid down onto the ground, his worn frame claiming rest. 

Sleep crept over his mind and dreams filled his vision. Haunting ghosts of his past played before him, mocking what was once his and what he lost. His happiness and few moments of peace thrown in his face as a treasure now warped and gone forever. In this state of dream, reality merged 

with nightmares of what he once remembered, the only link left to a life lost behind him, and in his uneasy sleep rest was far from him.

* * *

Morning broke upon the barren landscape and the cold bite of night slipped into the past. The air laid still on the dirt and hung thickly between the ground and the sky. 

Vanitas awoke and stirred his weary bones, only to find the child sleeping on his legs, one arm carefully wrapped around the unverse. With grunts he shoved it off and pulled himself up, waking it in process. 

The child rubbed its eyes and sat up, its sleepy gaze wandering around the room. The flood sitting beside it began making noises and nuzzling the child's elbow. Turning to greet it the child patted the floor and smiled, and then looked up at Vanitas. Vanitas glowered at it and slipped out of the room to find his master.

The old man isn't home. The dugout is empty, save the flood and child, and the old man is nowhere to be seen

_ Of course he isn't. Of course he dumps the stupid thing on me and leaves for days. What is the old man even doing? _

"We got more?"

Irritation budded and clambered out the hole of a window as Vanitas slowly turned to the little speaker. "What."

The child held on to the big empty pot with two hands, the flood draped on its shoulder and into the pot. It took a hesitant step forward and swung the pot forward. "More beans? I'm hungry…"

Keeping his face even Vanitas stared it down. He could feel the unverse out the window scrambling about the rocks avoiding the various floods who were slipping in and out the ground and biting each other. And the flood on the child's shoulder. He could feel the quiet sea of emotion in it, the waves gently lapping, but no turbulent storm.

It was strange and he didn't like it. That's not how things have been, and it's not right. Wayward emotions shouldn't be calm. Not when he isn't. 

"I'm hung-"

"Too bad, idiot. You ate it all."

The surprised and upset look on the child's face was oddly annoying, or upsetting. He couldn't quite put his finger on the emotion, and didn't even want to dwell on it long. "Nobody said that was yours, even, you stole the food."

"But-but I'm hungry…"

"So? I don't have any so leave me alone. Do you think I'm here to feed you?"

The child took a step back and shook his head slowly. Then, setting the pot down, ran back from where it came, it's little legs carrying the distance awkwardly.

Vanitas grumped to himself as he dug about the cabinet looking for anything edible that might be still left around. Some dried beans and stale bread was all his search brought, so settling them on the table he slipped outside to the cold windswept earth above.

It wasn't as chilly as yesterday, which made a slightly pleasant change, but not enough to ride the fact he was stuck once again with the helpless tiny thing that doomed itself in its own stupidity. Another whole day.

He purposefully left it inside this time so he wouldn't have to mess with it while he practiced. 

He summoned his keyblade and it willingly sprang into his hand with its familiar warmth of darkness. He turned and struck at whatever emotion mingled at his feet, with a stab of pain it slipped out of being and back to its host. 

He continued this process until the pain was too much, and slunk back to the dirt pit.

The child was sitting there, eating stale bread and patting the universe. Upon seeing Vanitas enter the room he sprung up and glanced about the room and nervously shifted his feet eyeing him. Vanitas regarded him coolly, expressing nothing.

"You sure you want to chew on that?"  _ Wait what do I care?  _ "It'll probably make you sick"

The child gulped and played with the hem of its shirt. "I wanted food…"

"Yeah sure. You'll really want to eat later today. Don't come crying to me." Oh no, he probably will. Great. 

The child shook its head vigorously and stared at Vanitas.

Vanitas only gave it a grunt. "Whatever, just leave me alone and don't cause trouble."

"I won't!" 

Vanitas poked at the dry beans sitting on the table and contemplated if it was worth the effort of cooking them to eat. The child sat down again and slowly continued gnawing on the bread. With a sigh Vanitas decided that yes, it wasn't worth it, and began his way back out the door before he heard a squeak behind him. 

_ Bet the unverse finally bit him. _ Vanitas smirked at the thought.

"You want bread?" The child's raised voice made him halt in his tracks and turn to face him. "'Cause I'm eating it!"

"Why would I eat that if it would make me sick?" This kids stupidity knew no bounds.

The child shrugged and made some sort of grunt around the food in its mouth. "'Cause you're hungry?"

"You're disgusting that's what."

His remark causes the child to sit back on his heels looking hurt and its gaze fell down to its lap, mouth clamped shut. 

Vanitas left the child behind him in the empty dugout to climb back up into the windy surface once more. Strange how there was fewer unverse around. Had he killed that many? It didn't really make sense but he didn't want to dwell on it long. Why ask for trouble, he wanted them gone anyway so. Maybe it was just actually working.

_ Take that old man, you said it was impossible. _

**Notes for the Chapter:**

> Ehhh I still don't know what I'm doing


End file.
